class Student:
    name = None
    def say_hi(self):
        print(f"大家好，我是{self.name}")
    def say_hi2(self,msg):
        print(f"大家好，我是{self.name},{msg}")

stu = Student()
stu.name = "ddd"
stu.say_hi()
stu.say_hi2("hello!")
